Taking a plane to such a low altitude - a technique called “terrain masking” - would have avoided detection on standard commercial radar equipment.

Investigators believe whoever was flying the Boeing 777 used terrain masking, which uses natural contours like hills and mountains, to hide the plane from satellite systems.

The airline's chief executive also revealed it was the co-pilot who said "all right, good night" before the aircraft went missing.

We are now closing our live blog. We will begin it again later today.

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6:18 am

Checks into the background of all the Chinese nationals on board the missing Malaysian jetliner have uncovered no links to terrorism.

The remarks by the Chinese ambassador in Kuala Lumpur will dampen speculation that Uighur separatists in far western Xinjiang province might have been involved with the disappearance of the Boeing 777 and its 239 passengers and crew early on March 8.

Chinese Ambassador to Malaysia Huang Huikang said today that background checks on Chinese nationals did not uncover any evidence suggesting they were involved in hijacking or an act of terrorism against the plane, according to state news agency Xinhua.

He also said that Chinese authorities had begun searching for the plane on its territory.

Malaysian police are investigating the pilots and ground engineers of the plane, and have asked intelligence agencies from countries with passengers on board to carry out background checks on those passengers.

6:24 am

An aviation expert has said that he believes the missing Malaysia Airlines flight came down following a fire rather than being brought down by terrorists.

Billie Vincent, former head of security for the Federal Aviation Administration in the U.S, said he did not believe a bomb was detonated.

He told website Air Traffic Management: "The data released thus far most likely points to a problem with hazardous materials. This scenario begins with an eruption of hazardous materials within the cargo hold - either improperly packaged or illegally shipped - or both."

He said that a fire would explain why flight MH370's communication systems were shut down one by one.

Mr Vinent, who played a key role of all U.S. hijackings in the 80s, said he believed that the plane's flight path may have been erratic because the pilot and co-pilot could not see the controls clearly enough for a return to Kuala Lumpur.

7:11 am

Australia's maritime safety agency drastically narrowed the search area in the southern Indian Ocean for the missing Malaysia Airlines plane today, but said the remote location, high seas and swift currents meant the task remained daunting.

The Australian Maritime Safety Authority (AMSA) shrunk its search field to a 600,000 sq km (230,000 sq mile) corridor, just 3 percent of the estimated 19 million sq km area in the Indian Ocean where the plane could be, based on satellite tracking data.

Still, the revised area is roughly the size of Spain and Portugal combined and will take the Australian-led southern search team several weeks to comb.

"A needle in a haystack remains a good analogy," John Young, general manager of the emergency response division of AMSA, told reporters. "The aircraft could have gone north or south and if it went south, this is AMSA's best estimate of where we should look with the few resources we have at our disposal for such a search."

AMSA said its revision of the search area was based on analysis of satellite data collected from the plane by theUnited States National Transportation Safety Board (NTSB) it received yesterday..

AMSA then streamlined that data further to account for water movements and changes in weather in the days since Flight MH370 disappeared 10 days ago.

"It's the result of some analysis of the possible movement of the aircraft," Young said. "There are some assumptions built in, including the speed of the aircraft."

The original search area for flight MH370 focused on a wide strip of territory either side of two arcs formed by satellite plots of the aircraft's last known possible position, an area measuring 38 million sq km.

7:17 am

Malaysia today rejected criticism from U.S. government officials that it has not been sharing as much information as it could with foreign governments about the disappearance of flight MH370.

Two U.S. security officials said yesterday that the Malaysia had still not invited the Federal Bureau of Investigation (FBI) to send a team to Kuala Lumpur to assist in the probe into the disappearance of Malaysian Airlines Flight MH370.

"I have been working with them," Malaysia's Defence and Acting Transport Minister Hishammuddin Hussein said when asked if the country had requested FBI help.

"It's up for the FBI to tell us if they need more experts to help because it's not for us to know what they have."

While Malaysia's police special branch has been providing some information to U.S. law enforcement and intelligence agencies, U.S. sources said, the FBI is only collaborating with Malaysian authorities via an agent, known as a "legal attache", assigned to the American Embassy in Kuala Lumpur.

The FBI and other U.S. law enforcement agencies, such as elements of the Department of Homeland Security, indicated some time ago they were eager to send teams to Kuala Lumpur, but will not do so unless formally invited.

Asked if any FBI staff had travelled from outside Malaysia, Hishammuddin said: "Once I have spoken to one FBI representative, I assume the whole FBI would be behind it."

The FBI has extensive experience in investigating plane crashes, including the crashes off the U.S. east coast of TWA 800 and Egyptair 990.

In the case of Egyptair 990, the FBI helped air safety investigators establish that the crash was caused by a suicidal co-pilot.

In the TWA 800 case, the FBI conducted a lengthy investigation that eventually helped the National Transportation Safety Board discredit theories that the plane was hit by a missile, but instead was brought down by a freak accident involving overheated fuel.

7:45 am

China has deployed 21 satellites in the search for the missing plane.

Foreign Ministry spokesman Hong Lei told a news briefing about the increase in technological help during a daily news briefing.

China has begun to searching for the missing jet in Chinese territory which covers a northern corridor through which the aircraft could have flown, state media said earlier.

No trace of the plane has been found more than a week after it vanished but investigators believe it was diverted by someone with deep knowledge of the plane and commercial navigation.

Two-thirds of the 239 people on board the flight are Chinese and their loved ones feel they are not being given the full story by Malaysian officials.

According to the Malay Mail Online Wen Wancheng, whose son is missing, said: "Relatives are very unsatisfied. So you hear them saying 'hunger strike'."

He added: "Now we have no news, and everyone is understandably worried. The relatives say they will go to the [Malaysian] embassy to find the ambassador.

"The Malaysian ambassador should be presenting himself here, but he's not."

9:23 am

European and U.S. runways are among those on the flight simulator that was found at pilot Zaharie Ahmad Shah's house.

A senior police officer said that analysis shows runways also included the Maldives, Sri Lanka, Diego Garcia and southern India.

"What we are trying to see is what were the runways that were frequently used," the officer said. "We also need to see what routes the pilot had been assigned to before. This will take time, so people cannot jump the gun just yet."

9:27 am

Today's press conference is due to start shortly.

Scores of journalists are in position at a hotel in Kuala Lumpur ready for the daily update on the missing flight.

9:38 am

The search has taken on an international dynamic within different countries. More about the diplomatics later.

Over the last 24 hours they have been working to narrow the search areas.

They are gathering information from satellite surveillance and radar data, increasing air and surface searches, and increasing the amount of technical support.

Malaysia has contacted all countries with access to satellites.

9:39 am

The northern corridor has been split into seven areas - 160,000 square nautical miles in total.

The same has been done with the southern corridor.

2.24million nautical square miles are now being searched in total.

"Malaysia could not do it on its own".

9:40 am

Mr Hussein is going through a list of the different hardware involved in the search.

It reveals the huge operation that is going on in both search areas.

9:43 am

Mr Hussein clarifies the timings of when the plane's ACARS system was turned off.

The switch off, he says, occurred between 1.07am and 1.37am.

The search for the plane is the priority.

9:44 am

He says there is even more commitment to help Malaysia since the search was widened.

He adds that thoughts are with the families of the people on board.

We are now hearing from the minister of foreign affairs.

9:45 am

There are 25 countries involved and there have been diplomatic notes sent to all countries.

9:47 am

It is a complex task to co-ordinate 25 different countries, but "politics is not important".

The foreign minister says "all efforts should be on finding the plane" after telling people not to profit from the disappearance.

9:50 am

Foreign minister, Anifah Aman, said that the prime minister has also been on the phone to other countries.

He said the country is relying on its good relations with other countries.

Mr Hussein has asked Indonesia to have another look at its information to see if there are any more clues.

He said the southern corridor is huge and there are only two countries - Indonesia and Australia - that are assisting with the search there. More help has been requested.

9:54 am

Mr Hussein criticises foreign press which he says is stirring up politics.

He re-iterated that the issue is "above politics" and the countries involved are focused on the search operation.

He said: "It is the foreign press which has brought that up. If I am not mistaken, it was The Daily Mail and CNN who said brought politics into this."

9:59 am

When asked when Malaysia will be able to say if the plane is the north or south corridor Mr Hussein said that they are possible locations.

All efforts, he said, are being made to reduce the area being searched.

That will be with satellites, radar, and using the assets available in the air or the sea.